In today's telecommunications and data processing industries, high speed, low-cost distribution and exchange of large amounts of information has become highly important. Manufacturing companies desire to distribute CAD/CAM design activities among premises. Publishing companies seek to design layouts electronically and share them among groups at different sites. Hospitals want to share detailed medical records in near real time. Until recently, all of these activities have been constrained by technology to a single building or campus. Companies have needs to lift constraints by using real-time networking technologies to replace overnight courier delivery. There is also a trend in both commerce and government toward data center consolidation. Organizations would like to serve local work groups from remote data centers. They need networking to do that and they need networking to back up these new, consolidated data centers so that they do not become a single point of failure for their entire operation.
Something that all these applications have in common is that they require that bits be passed at speeds higher than conventional T1 rate of 1.544 Mbps. Some applications demand higher speed on a sustained basis. Some applications require more bandwidth so that a burst can be delivered quickly. T1 or slower is what is typically installed in a wide area network. This represents a mismatch with the local area where the slowest speed generally used is 10 Mbps, i.e., in the Ethernet environment. The need for more bandwidth alone, however, is not enough to justify a new technology. Time division multiplexing (TDM) effectively scales up to SONET speeds of 155 Mbps. The problem with TDM is that it cannot provide true bandwidth-on-demand. New applications that are emerging present traffic to the network as large bursts of bits followed by lengthy interburst gaps.
ATM, when implemented properly, is able to make bandwidth available to carry the burst without disrupting other users. It is also able to make the bandwidth available to other users during the interburst period, thereby maintaining the cost-efficiency while carrying the applications in near real time.
In designing networks that use ATM technology, four factors require consideration: 1) complexity--complexity must appear to go away; networks should be kept as simple as possible; 2) economics--recurring bandwidth and operations costs must be contained; 3) transmission delay--the time it takes traffic to travel from origin to destination must be short; and 4) user demand--characteristics of the network must be appropriate to the application; that means information transfer may be required by the application to occur in near real time.
ATM combines the strengths of traditional packet switching--bandwidth efficiency--with those of circuit switching--high throughput, low delay, and transparency. Application traffic (voice, data, video, and image) is encapsulated in 53-byte cells for transport across the network. In contrast to traditional packet switching, no error processing occurs at the ATM layer, but is handled by the higher protocols in the attached DTE equipment. Therefore, ATM cells can be switched in hardware in gigabit speed with low delays. Because of the low latency and high throughput capabilities, ATM is the ideal technology to support these applications over the corporate network. It can support isochronous traffic, like voice and video, as well as bursty data, like local area internetworking, and traditional data, like SNA and X.25. The scalability of ATM makes it an attractive alternative for today's shared-media local area networks (LANs).
Since only meaningful information, such as active speech or payload data, is encapsulated in ATM cells for transfer across the network, bandwidth resources are used efficiently. By not wasting bandwidth resources for idle flags and silence periods during conversation, networks can be designed to make better use of available wide area facilities. ATM networks can be designed for least cost, while maintaining the quality of service (QoS) requirements of a wide variety of applications.
The challenges that must be overcome to attain seamless network vision are substantial. First, there are differences surrounding ATM deployment in the local versus wide area networks. These result in varying implementations in local area network and wide area network products that must interoperate to provide total network solutions. Second, there is the requirement for multi-vendor interoperability. Third, there are economic aspects that must be considered when migrating to the seamless ATM network.
Most of the focus in the local area network arena today has been put on pure data traffic. Voice and video are typically handled by specific communications equipment, completely separate from the local area network. Although multimedia is seen as one of the drivers of ATM to the desktop, current ATM LAN implementations are directed to the support of LAN data traffic only. On the other hand, a wide variety of traffic type traditionally has been supported over the wide area. To effectively integrate these traffic types with their specific performance criteria, ATM equipment must include sophisticated queuing, congestion, and routing algorithms.
The seamless network providing desktop-to-desktop multimedia networking is an exceedingly attractive solution that meets the high performance and flexibility required by future enterprise environments. To date, however, no method, system, or architecture having both an economically practical price and the desired level of performance exists that provides ATM network capabilities in the desktop environment.
Consequently, there is the need for a system that provides ATM network capabilities in the desktop environment.
There is a need for an ATM method and system that satisfactorily addresses the important considerations of local area and wide area network interoperability, multi-vendor interoperability, and economy in manufacture and implementation.
There is, in essence, the need for a method and system that satisfactorily addresses requirements in terms of both price and performance in bringing ATM to the desktop.